Hydraulic head integrator of relative vertical motion



7a. mwwwa & TESTENGU Feb. 4, 1941. c. A. YEATMAN HYDRAULIC HEAD INTEGRATOR OF RELATIVE VERTICAL MOTION Filed April 26, 1959 5 Sheets-Sheet l 13'. mmsumwa Q TESTING.

Feb. 4, 1941. c. A. YEATMAN HYDRAULIC HEAD INTEGRATOR 0F RELATIVE VERTICAL MOTION Filed April 26', 1939 5 Sheets-Sheet 2 73". MEASURING & TESTlNG. 1mm

Feb. 4, 1941; c N 2,230,280

HYDRAULIC HEAD INTEGRATOR OF RELATIVE VERTICAL MOTION Filed April 26, 1939 I 5 Sheets-Sheet 3 W CD3SQ' y 2 9 526") WWW 3. MEASURfNG z TESWNG.

Feb. 4, 1941. c. A. YEATMAN HYDRAULIC HEAD INTEGRATOR OF RELATIVE VERTICAL MOTION Filed April 26, 1939 5 Sheets-Sheet .4

deal/M?- 73. MEASURING 8; TE Tl'NG.

Feb. 4, 1941. c. A. YEATMAN 2,230,280

HYDRAULIC HEAD INTEGRATOR OF RELATIVE VERTICAL MOTION Filed April 26, 1939 5 Sheets-Sheet 5 WWW.

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Patented Feb. 4, 1941 UNITED STATES PATENT OFFICE HYDRAULIC HEAD INTEGRATOR OF RELA- TIVE VERTICAL MOTION 2 Claims.

In the broad or general aspects of my invention, it comprehends recording the hydraulic head pressure and changes thereof between two objects which have a relative vertical movement and are connected by a hydraulic column, that is, a liquid column. Therefore by my invention, for instance if one object is stationary and the other has a vertical movement relative thereto, by means of a suitable conduit I form a liquid column between the two objects and at the lower object I employ a recording instrument responsive to the hydraulic head and changes thereof due to the increasing or decreasing heighth of the liquid column. As my invention in its practical applications requires usage where at least one of the objects is subject to vibration, I in addition provide means in the hydraulic column for damping vibrations developed in the uppermost of the two objects as such vibrations may cause vibrations or surges in the liquid column. Hence, included in my invention in the structure for forming the liquid column is a means for damping vibrations communicated to such column and a pressure recording instrument which makes a record of the changes of hydraulic head pressure without being subject to the minor changes of fluctuations of hydraulic head due to Vibration and minor surges.

Another feature of my invention includes the recording of the hydraulic head, that is, the pressures developed by the changing head of the liquid column in relation to time in which such recording is drawn on a suitable chart. The record shows changes of hydraulic head in reference to time periods and. if calibrated may show difference of elevation between the two objects for a period of time and the rate of change of elevation. My invention further comprehends with the hydraulic equipment for forming the record of the change of elevation in reference to time by recording this in the form of drawn curves which may be quite regular but differing slopes depending on constant vertical speeds extending for comparatively long times. or the curves may indicate increase or decrease relative to a constant speed. Therefore in order to interpret from the drawn curves of the recorded chart, my invention also includes a transparent template on which I have curves imprinted, each curve showing a certain specific speed of vertical movement of one of the objects in reference to the other. By superimposing the template on the record chart and aligning the curves for specific speeds on a template with similar curves on the chart, I am enabled to tabulate and if desired, make a graph showing the speed of vertical movement at any definite time periods or' between any two definite elevations. Therefore by the combinational use of the chart and the template and without the necessity of calculation, there may be made either tabulations or graph charts showing speeds of vertical movement in reference to the successive elevations of the relatively stationary and relatively vertical movable object.

Considering the feature of my invention relating to the specific drilling speed indicator or recorder, this is used in conjunction with equipment for the rotary hydraulic type of drilling in which the drill pipe is rotated through the medium of a kelly and a rotary table with the hydraulic slushing fluid being pumped downwardly through the kelly and the pipe through the medium of a hydraulic swivel block. The particular features of my inventionemploy a hydraulic reservoir which may be attached to the swivel block at some place where it is not subject to rotation, then by means of a flexible hose which is reinforced to prevent collapse, a column of the liquid from the reservoir is lead to a container located preferably below the derrick floor at a suitable place convenient for changing the record charts and for reading the instrument. The container is connected to a recording pressure gauge of a time actuated type, the container preferably having a gas or air pocket so that the changes of pressure are accurately indicated and recorded on the recorder. Therefore in the use of my invention when the reservoir is at a high position for instance in commencing drilling after installing a stand of drill pipe, the container is under the pressure of a relatively high hydraulic head, that is, the difference of elevation between the reservoir and the container develops a hydraulic head which at commencement of the drilling is greatest as the last fitted stand comes into operation. Then as the bit cuts into the formation and lowers the drill pipe, kelly and the swivel block, manifestly the reservoir is lowered and this gives a decreased hydraulic head in the container and therefore the pressure recording gauge shows this reduced pressure. Then as above mentioned as the recording gauge is operated by a timing mechanism, a graph is drawn on the record chart showing the decreasing pressures from the time the last installed stand is brought into operation until the desired depth has been drilled by this stand. The pressure gauge shows the lifting of the kelly and the drill string for the purposes of installing a secnd stand of drill pipe and then shows the pressure at the commencement of drilling using this newly installed stand, the gauge therefore gives another section of the chart with the decreasing pressures until this latest stand has been lowered the desired amount. Hence for instance in considering a record running for 24 hours, the various stands by which the bit has been worked down into the hole is shown on the chart and the different pressures on a recording gauge.

Another feature of my invention consists of a template and the manner of using this in conjunction with the record made of the speed indicator portion of the instrument, that is, the simple part of the instrument giving the different hydraulic pressures according to the difference of elevation of the reservoir and the container. For convenience I make the recordings on a conventional disk-like record paper, this being graduated in hours preferably the 24 hours of the day and showing the day and night period, hence one feature of my invention is the making of the pressure chart in conjunction with the running in of the stands of drill pipe. Another detailed feature of my invention relates to the construction and use of a template utilized to interpret the speeds of drilling as obtained from the record chart. Hence the characteristics of the template is a circular chart made to conform to the record paper with somewhat similar circles and on this I draw curves of drilling speed such as so many feet per hour. For instance these curves may illustrate the drilling speed per hour running from feet per hour or less to 120 or higher rate per hour. Manifestly there is a considerable difference in the shape of the curves in accordance with the drilling rate.

My invention also comprehends the using of the template in connection with the records. By superimposing the template made on transparent material such as Celluloid, the various curves may be aligned with portions of the record indicating the rate of change of the hydraulic head between the reservoir and the container of the recording instrument. A tabulation may be made of the various changes of speed which is correlated to the particular hour and part or an hour of the day. In view of the fact that in drilling a record is maintained of the pressure on the bit and the depth of the bit at the particular hours and part of an hour which corresponds with the record, the tabulation then comprises a record showing the speed of drilling at the particular depth in the well.

The drawn chart and template may be used in making and interpreting a graph chart which shows the rate of drilling at particular depths in the well. For instance this graph chart may be arranged with the axis of abscissa being the depths in the well, for instance indicated at every 100 feet. Then the axis of ordinates is a speed of drilling per hour, for instance running from zero through 5, 10, 20, etc., to the highest speed per hour. The graph chart may be drawn either from the tabulation above designated or directly from the record by using the template.

A corollary of my invention of the combinational use of the drawn chart and the template resides in its use to determine geological formations when one or more wells are drilled in the same field. For instance presuming a first well is drilled in a field, the graph chart clearly indicates the soft places in the formation where the drilling-is at high speed. It also indicates the hard spots or zones in which the rate of penetration is slow, all of these being shown on the chart at their correct depth in the well. Then when a second or succeeding wells are drilled in the same field where geologically it is known that the formations are somewhat the same, the graph chart of the subsequent drillings show similar soft and hard places due to the different rate of drilling and the depth at which these occur, hence by comparing two or more graph charts, a determination can be made of similar characteristics of earth formation as to different wells in the same field. Then when in one well the particular characteristics shown before breaking into the oil sand or formation is clearly shown, the graph charts for subsequent wells give an indication as to where and when the similar drilling into the oil formation may be expected.

My invention is illustrated in the accompanying drawings, in which:

Fig. 1 is an elevation in a manner of a diagram of the drilling speed indicator showing the mounting in a well derrick.

Fig. 2 is a vertical section on the line 22 of Fig. 3 of the reservoir for the liquid.

Fig. 3 is a plan of the reservoir taken in the direction of the arrow 3 of Fig. 2.

Fig. 4 is a vertical section of the liquid container showing a conventional recording gauge in elevation.

Fig. 5is a face view of a recording of actual drilling in a well.

Fig. 6 is a face view of a transparent template to be used with the record in interpreting the speed of drilling.

Fig. 7 is a graph chart made from the record of Fig. 5.

Fig. 8 is a graph chart of a well drilling made from graphs similar to Fig. 5 showing in full lines the graph of well No. l and superposed on the same graph is the chart shown in dotted lines of well No. 2.

Fig. 9 is a graph chart of well No. 2.

Figs. 10 and 11 present a full sized record of a portion of the drilling of well No. 1 in which an overlap of the record card is illustrated.

Fig. 12 is an elevation of the drilling speed indicator somewhat similar to Fig. 1 but showing a modification in which the hydraulic head is increased as the drilling progresses.

Referring first to the speed indicator equipment of Figs. 1 through 4, this indicates part of an oil well derrick designated by the numeral II in which one of the posts or one side is designated by the numeral I2, the derrick floor I3, the rotary' table [4, the kelly l5 and the swivel block it. Such swivel block has the usual connection for the hose to transmit the pumped slushing mud. .These features are standard equipment, the kelly being connected to the string of drill pipe and as the slushing mud is forced down through the swivel block, the kelly and the string of drill pipe, the kelly is rotated thus rotating the drill pipe and the bit at the bottom of the well. In the illustrations of the derrick construction and associated parts, I omit for sake of simplicity all matters having to do with the operation of the rotary table and the lowering of the swivel block with the kelly and the string of drill pipe. It is to be understood that the usual instruments are utilized such as gauges to determine the weight on the bit and if desired speed indicators showing the rate of rotation of the rotary table and hence of the kelly and drill pipe.

lLQH mm 'Inmy invention of the speed indicator which may be designated generally by the numeral 25, this employs a reservoir assembly 26 which illustrates a c lindrical reservoir cannister 21 closed at the top and bottom except for a vent opening 28- in the top. A substantial supporting plate 29 is secured to the walls of the cannister preferably by Welding and has a bolt hole 30 by which it is bolted to a bolt on the swivel block or other suitable structure. In addition as a safety element I have 'a chain 3| preferably secured to the top of the cannister. This has a bolt washer 3! at the end which may be attached to a stud on a swivel block or the like. This is a safety element in case through accident the cannister should be knocked off the bolt attaching it to the swivel block or other structure. The chain and its washer is not utilized as a means for supporting the reservoir. Adjacent the bottom of the reservoir there is a hose connection 32. A flexible hose 33, of which I use a type known in the trade as oxygen hose such as is commonly used in welding'operations, is attached at its upper end to the hose connection 32 and is looped over a hose fastening 34 secured to the derrick standpipe I2 of the side of the derrick. This is to permit forming of a drop loop 35 of the hose as the drill increases the depth of the hole being bored and the kelly manifestly moves downwardly in relation to the rotary table and the derrick floor. From the hose fastening 34 there is a drop section 36 of the hose which leads downwardly in a suitably protected manner to a position below the derrick floor.

Located in a suitable instrument room below the derrick floor I install the recorder assembly 40. This has a substantial container 4i illustrated as cylindrical and closed at both the bottom and the top forming an air tight structure. Adjacent the bottom I provide a hose connection 42 with a valve 43, the drop section 36 being attached to the hose connection. Also connected to the container preferably adjacent its bottom there is a valved filling connection 44. With this construction the liquid of the hydraulic operating liquid contained at 45 fills the lower part of the container, there being an air pocket 46 in the upper part. pressure gauge, 5|] is connected to the container, this having a pipe connection 5|. The gauge is preferably mounted on an instrument panel and it is not necessary that the pipe be supported by the container or that the connection be by a short length of pipe. The recording gauge may be of any suitable type. I prefer however to use a type in which a paper disk properly graduated as to the hours of the day for a 24 hour period is utilized, the pen of the gauge making a record mark on the disk, such disk being rotated by clock-work or the equivalent.

The theory of the operation of the speed indicator is substantially as follows: In the practice of drilling, the kelly is disconnected from the string of drill pipe in order to install an additional stand to increase the drilling and then presuming the kelly is connected up and ready for drilling, manifestly the swivel block will be in a relatively high position in reference to the rotary table. In the illustration of Fig. l the kelly may be considered as lowered to somewhat lower than half the length of a stand so that when the kelly is in an upper position the loop 35 of the hose is stretched upwardly, however there is sufficient slack inthe hose that no matter how high A conventional time recording the kelly and the swivel block is raised, there is no danger of breaking the connecting hose 33.

Manifestly when the swivel block is in a high position in commencing drilling, the reservoir 26 is likewise in a high position relative to the container 4|. When there is the greatest difference in elevation between the reservoir and the container, the highest hydraulic head is developed in the container, this being the highest pressure. As above noted there is an air vent 28 to the reservoir so that the air in the reservoir is at atmospheric pressure. The air pocket 46 in the container manifestly is reduced in size by the air being compressed by the liquid in the container. It is of course manifest that there must always be sufiicient liquid to maintain the necessary supply in the reservoir, the length of hose and the container. The whole equipment may be filled through the valved filling connection 44. The actual drilling is under the control of the drill man as in the ordinary and conventional drilling practice who regulates the speed of the rotary table, the weight on the boring bit at the bottom of the hole and maintains a lowering of the bit depending upon the formation and the speed of making the hole. As above mentioned the usual gauges such as gauges showing the weight on the bit are utilized as well as the other instruments as in the conventional and approved practice of drilling. As the bit bores the hole in the bottom of the well, manifestly the drill string, kelly and swivel block are lowered, hence the reservoir is lowered relative to the container 4|. Therefore the hydraulic head or pressure in the container continually decreases during the drilling at a, length of a stand. In view of the fact that the recording gauge maintains a record of pressures correlated with time, the pen of the gauge forms a line on the record disk depicting this decreasing pressure and any changes of the pressure. Manifestly for instance when the drilling is Very fast as through soft formation, there is a much greater difference of pressure shown on the disk record in an interval of time than when the drilling is very slow such as in going through hard formation in for instance a unit of time. Therefore by an interpretation of the record, a person skilled in its use and using for $1? fl fill instance a template hereunder described, may at i any time ascertain the rate of drilling.

In view of the fact that while the drill is in operation the depth of the bit is definitely known, for instance in drilling in a length of stand of drill pipe between the top and bottom of the downward run and at the intermediate stages and this record of the time is also kept of the different depths of drilling, therefore manifestly from the record entries may be made thereon showing the depth of the bit at any particular hour or fraction of an hour of the 24 hour day and hence the speed of drilling may be correlated to the penetration at any specific depth below ground.

It will be noted that on a study of the record hereunder described in connection with the drawings that there are a nmuber of lines drawn by the pen of the recording gauge which are not directly pertinent to the actual drilling, these being due to vertical movements of the kelly and the swivel in adding joints of drill pipe, etc., and some of which show a time period of no drilling with the bit raised above the bottom of the hole. Frequently derricks are equipped with two rat holes, one in which the kelly with the swivel mounted thereon is dropped when pulling the tools out of the well and again running them in designated as well No. 1.

the well with the new bit. The other rat hole is usually used for a joint of drill pipe placed in the second rat hole by the use of the cathead line. The kelly when a sufficient amount of drilling has been accomplished to require addition of another joint is lifted thus bringing the upper end of the drill pipe above the rotary table and this being then supported by the slips while the kelly is shifted laterally and threaded to the joint of drill pipe in the second rat hole. The kelly with this joint is then aligned with the drill string suspended by the slips and the new joint is connected in the string. This manifestly raises the reservoir much above the elevation at which the drilling commences. The pen would go completely off the record chart were it not that I use a retarding stop which produces an irregular mark where the kelly is raised for this purpose of adding another joint.

Another important feature of my invention relates to the fact that when the kelly is placed in the first rat hole, the swivel being left on the kelly, that there is no up and down movement causing a change of elevation between the reservoir and the container, hence at these periods there is a concentric line drawn on the record by the pen.

Referring therefore to the graphs, templates and graph charts, Fig. 5 depicts a recording in a reduced size of the actual record of a well This record is designated by the numeral I and represents a paper disk with the hour lines If extending from the peripheral edge towards the center. The card has the hours marked for the period of the day by the double peripheral lines I2 and the night period by the solid peripheral lines I2. Referring to Fig. 5, the preliminary record of the drilling, noted by the numeral I3 is shortly after 12 oclock midnight. The actual drilling commenced at the point I4 at a depth of 7651 feet and continued until about 4 a. m., note I5, where a joint of drill pipe was added to the drill string indicated by the record line IS. The next drilling started at 4:15. a. m., note 11 and continued until reaching the depth at I8 of 7704 feet, at 7:30 a. m. A round trip was then made from I9 to 80, at 8 a. m. of the daylight period through to 2 p. m. when the complete drill string was removed from the well and then run again into the hole. The drilling re-commenced at 8I at the depth of 7704 feet and continued to the point 8|, the time period being from 2:45 p. m. until 6:45 p. m. The lines 82 indicate the adding of one joint of drill pipe with drilling commencing at 83 at approximately 7:15 p. m. This drilling was carried on until a depth, indicated at 84, of 7762 feet was reached, such drilling period carrying through the time from 7:15 p. in. until about 10:30 p; m.

For tabulation of and transfer of the drilling speeds to a graph chart, I utilize a template illustrated in Fig. 6 on a reduced scale, this being designated by the numeral I00, the full size corresponding to full sized record of Figs. 10 and 11. The record of Fig. and the template of Fig. 6 are presented on the same scale, both reduced from the actual size. The template is preferably a transparent disk of sheet material indicated at IOI such as Celluloid or other suitable material. There are a series of circles I02 drawn thereon although these are mainly for the purpose of interpolating depths and intervals drilled, in the full size the intervals between circles I02 represent 2 feet of drilling. This template whose center aligns with the center of the record, is a series of speed curves I03 and at the outer end of each of these lines or curves I have numeral indicia I04 indicating the number of feet per hour of the drilling corresponding to each curve. It will be noted that at the low speed of 5 feet per hour shown by the line I05 that the curve may be considered as a comparatively close spiral, however it is not a true spiral from the center. At the speed of feet per hour indicated by the curve I06, there is a less steep or confining spiral. These may be all considered as concave relative to the center of the template until at approximately the curves indicated at I0! and I08 at 45 to 50 feet per hour, the curves change and from the curve I09 representing 55 feet per hour, the curves reverse and depart quite decidedly from the appearance of a spiral. The curve IIO represents the highest speed on the template, this being 120 feet per hour but it will be understood that the template might be carried on to much higher speeds if necessary. It will also be apparent that curves at a lower speed than 5 feet per hour as I05 could also be drawn and intermediate curves between the 5, 10 and also drawn in, however it is quite simple in using the template on the record to interpolate the speed per hour.

The manner of using the template in conjunction with the record is to center the template on the record and then rotate this so that a portion of one of the curves is closest to the particular curve being studied. Thus for instance referring to the record of Fig. 5 and starting the curve from the point I5 at a depth of 7652 feet, it will be found that the curve is quite close to that of I06 at 10 feet per hour but slightly less than this. The drilling curve from the point I4 to the point I5 is obtained by interpolating between the curves I05 and I06. The procedure is continued for the other parts of the record.

A graph chart made up and interposed from the record of Fig. 5 using the template of Fig. 6 is shown in the graph chart of Fig. 7. Such graph chart is designated by the assembly numeral II5. All of these graph charts have the characteristicsof the axis of abscissa indicated at H6, being in lineal feet and graduated as to the depth of the Well. The axis of ordinates II! is graduated as to speed of drilling in feet per minute. It is to be noted that in the particular graph chart of Fig. 7 that although this shows a depth of drilling from 7500 to 7900 feet, the particular record of Fig. 5 only carries the drilling as above mentioned from a-depth of 7652 feet to a depth of 7762. On account of the slow speed of drilling, this being 'mostly below 10 feet per hour, that the indications are that this drilling is through hard material, the drilling thus being quite slow. There is only approximately from the depth of 7715 feet to 7750 feet that the drilling was at the rate of 10 feet per hour. In view of the fact that a tabulation is kept of the drilling record at the various hours of the day, the 'particular depth of intermediate points not subsequently marked on the record may readily be ll terpolated and thus quite an accurate graph record is obtained.

In Figs. 10 and 111 show a full sized record of drilling in well No. 1 between the depths of 5738 feet and 7255 feet, the graph chart of which is illustrated in part in Fig. No. 8 in thefull lines. This record shows considerable variation in the drilling at relatively high to comparatively low speeds. In these figures the parts of the record card are identified bythe numerals I Id, MLASURING r lIzSIING.

tat.

it It "it if tittii W" to the part of the card of Fig. and I2I to the part of Fig. 11. These records indicate the drilling' commencing at point I22, Fig. 10 at a depth of 6738' feet shortly after 12 midnight. The drilling is quite rapid and a number of stands or joints of, drill pipe being added and the succeeding drilling points starting at I23, I24, I25, I26, I21, I28, I29, I30 and I3I. There is then a period of irregular drilling commencing at point I32 between the hours of 6 and 8 a. m. The tracing inthe area I33 indicates a certain stand drilled down as far as possible with the swivel in close proximity to the rotary table and the operator moving a joint of drill pipe ready to be connected in the stand, for instance the joint being placed in the second rat hole provided for the joints of pipe. The high point I34 indicates the connection of a joint of drill pipe to the kelly and the raising of the kelly for attaching the joint or stand to the drill string suspended by the slips in -the rotary table. The small tip I35 and others of a similar nature indicate the action of a retarding stop on the pinof the pressure recorder preventing this from moving entirely off the scale. Point I36 indicates the drilling being again commenced, the irregular tracing I31 is probably due to the driller suspending the drill string and tools before lowering to the bottom of the well while the derrick-floor has been washed down. After this a point of commencing drilling is indicated at I38, a following point at I39, the drilling being carried down to a point indicated I40 which was at a depth of 7134 feet. At the concentric portion of the tracing I4I the tools are removed from the well and again run therein, this being designated in the art as a round trip. It will be noted that this occupied the time period from about 11:30 of the midday until about 4:15 p. m., noted on the section I20, that is, Fig. 11 of the record. The drilling again started at the point I42, Fig. 11 at a depth of 7134, this being at approximately 4:45 p. m. A joint was added and continued drilling commenced at the point I43. After adding stands succeeding drillings commenced at the point I44 and I45, joints of pipe being added and at I46 the drilling stopped at the point I41 at a depth of 7256 feet at approximately 10:15 p. m.

A graph chart of, this well No. 1 is illustrated in Fig. 8 showing this in full lines designated by the numeral I00 running from the depths of 7000 feet to slightly over 7400, however the record of Figs. 10 and 11 identified by the numerals I and I2I starts below the part of the charted graph as above mentioned at 6738 feet and runs to the point indicated at I6I, 7258 feet. The point of drilling where the tools are removed indicated at I62 was at a depth of 7134 feet. From this charted graph it will be seenthat the various speeds of drilling as shown in Figs. 10 and 11 which come within the limits of the graph are clearly depicted and illustrate a considerable variation in speed drilling, thus showing the drilling through relatively soft and very hard material. I v

The graph chart of Fig. 9 designated by the numeral I10 is of a well designated No. 2 in the same field. The records of this drilling are not illustrated. The charted line "I shows the speeds of drilling at various depths illustrating the localities of relatively high speed through comparatively soft material and the distances through which the drilling was at low speed in hard material. In this drilling in the same field, the same formations were encountered. It is to be noted however that they are located at different depths compared with the graph chart of Fig. 8.

In order to make a comparison between the graphs of the charts of Figs. 8 and 9 of wells No. 1 and 2 in the same field, the graph of Fig. 9, well No. 2 has been drawn on the chart of Fig. 8 and indicated by the dotted lines I12. The lines of the chart of III of Fig. 9 and I12 of Fig. 8 are identical except for the transposition as to depth. The depths corresponding to the dotted line chart are indicated by the slanting numerals I13 as to depth.

It will be noted that by the records and the charts that these give a comparative rather than absolute data whereas such factors as the human element and the condition of the tools have a pronounced effect on the absolute data, they have very little influence on obtaining comparative information. By this comparative information or data I refer to the recordings of marked changes in drilling progress, hence it is not necessary in making the graph charts to use great precision in transcribing the records to a feet per hour basis; considerable interpolation may be used in the procedure, however from the record of a first well in a field in this case designated as well No. 1 and the record while drilling of another well in the same field designated herein as well No. 2, the decided similarity in characteristics, especially as to the distances of slow drilling indicating hard material showing that the bit has encountered the same type of formation in the two wells, therefore a geological study and interpretation of the underground formation especially as it effects the drilling may be acquired and used in succeeding wells drilled in the same field after drilling a first well. Of course the drillers are very desirous of knowing when they will penetrate into the oil bearing sands or formation. While the graphs and charts of these drawings do not carry the depth to the oil bearing strata, it has been found that after a first Well has been drilled in a field that the subsequent wells drilled in the same field enable a clear showing to be obtained by the records and the graph charts as to when the hard cap is about to be penetrated and is penetrated into the oil bearing formations.

Another important feature of my invention and of valuable use thereof, is in making a precise study of the effect of different weights applied on the bit in the cutting of the hole and also a study of the action of different types and makes of bit. The study can also include the rotation speed, therefore by changing the variables such as the rotation speed and the weight on the bit, a record may be obtained of the speed of cutting the hole and this may be transferred to a graph chart, and hence the most desirable factor as to speed and weight may be accurately determined. Also as by the records and charts, a determination may be obtained of the drilling in the same formation in the same or different wells, accurate tests of different makes and types of bits may be obtained which of course is valuable to the well drillers and the companies drilling the wells.

In Fig. 12 I illustrate a modified construction over that of Fig. 1 which under some conditions is more convenient for usage. In this arrangement the hydraulic head increases as the depth of the well is increased by drilling. In this illustration the derrick side or post with a substantial beam extending outward from the derrick is indicated by the numeral I2. The speed indicator designated by the assembly numeral includes the suspended reservoir assembly 26, this having a bail and suspended by a light flexible cable 29' from the swivel block 5', the cables passing over the sheaves on the beam and having a clear and straight drop for the reservoir. The flexible hose 33' leads from the reservoir to the recording assembly 4|! located in a fixed position usually below the derrick floor. This has a container 4| of a type similar to that described connected to the recording pressure gauge In the operation of this device it is manifest that as the drilling progresses running in a joint or stand of drill pipe, that the hydraulic head increases as the reservoir rises but this gives a change in hydraulic head due to the vertical lifter movement of the reservoir. With this construction when the device is not used for recording it is obvious that the cable 29 may be readily disconnected from the swivel block and attached in any suitable manner to the derrick either leaving the reservoir suspended or in a lower position. It will thus be Seen that my invention broadly comprehends the use of changing hydraulic head between the res- 'ervoir and the recording assembly no matter whether this is a decreasing head during a drilling run as illustrated in Fig. 1 or an increasing head as illustrated by the construction of Fig. 12.

Various changes may be made in the details of the construction without departing from the spirit or scope of the invention as defined by the appended claims.

I claim:

1. In a device as described, the combination of a closed liquid container adapted to have liquid in the bottom and a gas pocket thereabove, a pressureindicator with a connection to the container, a flexible conduit connected to the container below the gas pocket and containing a liquid to form a liquid column, means for mounting the closed container and the pressure indicator on a first object and means for connecting the upper portion of the flexible conduit to a second object whereby the vertical change of elevation of the second object in reference to the first object causes a change in the heighth of the liquid column and thereby a change in the indicated hydraulic head of the column by the pressure indicator.

2. In a device as described, the combination of a closed liquid container having liquid in the bottom and a gas pocket thereabove, a combined time indicating and hydraulic head pressure recording instrument with a'pressure connection to the liquid of the container, the container being constructed and adapted for mounting on a first relatively fixed object, a reservoir having a connection to atmosphere constructed and adapted for attachment to a second and relatively movable object, a flexible conduit connected between the container and the liquid therein and the reservoir and forming a hydraulic column, such hydraulic column changing the efieotive hydraulic head pressure with vertical changes of the first and second objects, the combined time indicator and hydraulic pressure recorder being thereby adapted to indicate the speed of change of the vertical elevation between the first and second objects.

CHARLES A. YEATMAN. 

